Such a power semiconductor module has already been described in Laid-Open Specification DE 195 30 264 A1. This is a so-called pressure-contact semiconductor module, in which a plurality of semiconductor chips are arranged with their first main electrode on a base plate. The second main electrodes of the chips make electrical contact with a plurality of contact stamps. The base plate is connected to first main connection, and the contact stamp is connected to a second main connection.
It is difficult to solder the individual chips at the same level, and even harder to keep them plane-parallel. In the abovementioned Laid-Open Specification, the position of each individual contact stamp is set individually on the basis of the distance between the semiconductor chip with which contact is to be made, and the second main connection. This allows the requirements for plane-parallelity of the chips surfaces to be reduced. The position of the contact stamps, which are mounted such that they can move and are of a constant length, is set by means of a spring which is arranged in a hole provided to accommodate the contact stamps. The force acting on the module is transmitted to the individual semiconductor chips via these springs.
The solution specified in the abovementioned Laid-Open Specification has the disadvantage that the current must flow through the spring. The electrical conductivity of the spring itself and, in particular, that of the junction between the spring and the contact stamp or the second main connection, is, however, often inadequate.